Milton Secondary Suite Guide
Milton now allows up to 3 ARUs per lot — here is how to register, permit, and build yours.
Permit Fees
$340 registration + building permit (varies by project value)
Timeline
3-5 months from application to occupancy
Region
Halton Region
Overview
Milton Town Council approved amendments to allow up to three additional residential units (ARUs) on a lot containing a detached, semi-detached, or townhouse in urban areas. The town has a dedicated ARU Building Permit Application Guide (updated June 2025) that walks you through drawings, inspections, and construction requirements.
All ARUs must be self-contained with a kitchen, sleeping area, and bathroom for exclusive use. Registration is mandatory — $340 one-time fee per ARU, done in person at Town Hall or online.
Milton Requirements
| Requirement | Standard | Notes |
|---|---|---|
Ceiling Height | 1.95 m (6'5") minimum | OBC standard. Measure from finished floor to finished ceiling. Beams and ducts can project below if they cover less than 20% of room area. |
Fire Separation | 1-hour fire-rated assembly | 5/8" Type X gypsum both sides of demising assembly. Full tested system required — not just drywall thickness. |
Egress Windows | 0.35 m² unobstructed opening per bedroom | No dimension less than 380 mm. Window wells required for below-grade bedrooms. |
Parking | Check current zoning by-law | Milton zoning amendments in progress — parking requirements may change. Contact Zoning Division: 905-878-7252 x2329. |
Electrical | Separate sub-panel + ESA permit | ESA inspection mandatory. Dedicated circuits for kitchen, bathroom, laundry. |
Plumbing | Verify drain capacity + backwater valve | Backwater valve required. Check fixture unit count against existing drain capacity. |
HVAC | Independent heating or zone control | Separate thermostat required. Mini-split common for basement ARUs. |
Zoning | Up to 3 ARUs in urban residential zones | Council approved amendments for detached, semi, and townhouse. Rural zones may have different rules. |
Ontario Building Code Standards (Apply Everywhere)
These OBC requirements apply to all secondary suites in Ontario, regardless of municipality.
Fire Separation: 1-hour fire-rated ceiling assembly (Type X drywall)
Required between dwelling units. 2024 OBC update: smoke-tight barriers may replace full fire separations in some configurations. Inspected before occupancy permit.
Egress Windows: Min 0.35 m² openable area per bedroom
Bottom of opening max 1.5 m above floor. Must be rescuable from outside.
Electrical: Separate 100A panel minimum
ESA inspection mandatory. AFCI breakers required for bedrooms.
Plumbing: Separate water meter + backwater valve
Drainage must meet Part 7 standards. Backflow prevention required.
HVAC: Independent heating system OR zone control
Ventilation: min 10 L/s per occupant. HRV recommended.
Permit Process
Step-by-step guide to getting your Milton building permit
Total Timeline
3-5 months from application to occupancy
Permit Fees
$340 registration + building permit (varies by project value)
Review ARU Guide
1-2 daysDownload Milton's ARU Building Permit Application Guide (June 2025 edition). Review drawing requirements, inspection stages, and construction standards.
Prepare Drawings
1-3 weeksHire a qualified designer to prepare floor plans, sections, and details showing fire separation, egress, plumbing, electrical, and HVAC.
Submit Building Permit
1 daySubmit application with drawings to Milton Building Department. Pay permit fees.
Plan Review
4-6 weeksMilton reviews drawings for OBC, zoning, and fire code compliance. Expect revision requests.
Construction + Inspections
8-12 weeksBuild per approved drawings. Call for inspections at framing, insulation, plumbing, electrical, and final stages.
Register ARU
1-2 weeksOnce all inspections pass, register your ARU with the town. One-time fee of $340 per unit.
Incentives & Rebates
Federal and provincial programs that can help fund your secondary suite project. See all rebates available in Milton
Canada Secondary Suite Loan
Up to $80,000 at 2% interest
Federal loan program. 15-year repayment. Available to homeowners building new secondary suites.
Ontario Secondary Suite Incentive
Up to $40,000 forgivable
Rent at below-market rates for 5 years — loan forgiven at 20% per year.
Pro tip: You can stack federal and provincial programs for up to $120,000 in combined funding. Apply for federal programs first, then provincial.
Milton-Specific Tips
- ARU registration is MANDATORY — $340 one-time fee per unit. Non-compliance fines start at $10,000+.
- Milton's ARU Building Permit Application Guide (June 2025) is the best starting resource.
- Zoning amendments allow up to 3 ARUs in urban residential areas — check your specific zone.
- Contact Zoning Division at 905-878-7252 x2329 for zoning-specific questions.
- Milton actively enforces registration — unregistered units face fines and potential court orders.
Secondary Suite Guides for Nearby Cities
Compare requirements and incentives in other Ontario municipalities.
Related Services
Common trades and services for basement apartment projects.
Complete Guide
Province-wide secondary suite guide with all requirements.
Learn moreUnderpinning
Excavate to lower floor and meet ceiling height requirements.
Learn moreWaterproofing
Fix moisture issues before finishing basement apartment.
Learn moreElectrical
Panel upgrades, separate meters, and ESA permits.
Learn morePlumbing
Drain capacity, backwater valves, and separate water meters.
Learn moreCommon Questions
Get a Quote for Your Milton Basement Apartment
Connect with verified contractors who specialize in secondary suite construction. Escrow-protected payments, GPS-verified work, and permanent records.